import java.util.*;

/*
 * public class ListNode {
 *   int val;
 *   ListNode next = null;
 *   public ListNode(int val) {
 *     this.val = val;
 *   }
 * }
 */

public class Solution10 {
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 
     * @param head ListNode类 
     * @param n int整型 
     * @return ListNode类
     */
    public ListNode removeNthFromEnd (ListNode head, int n) {
        // write code here
        ListNode dum = new ListNode(0);
        dum.next = head;
        ListNode fast = dum;
        ListNode slow = fast;
        while(n != 0) {
            n--;
            if(fast != null) {
                fast = fast.next;
            }else {
                return head;
            }
        }
        while(fast.next != null) {
            fast = fast.next;
            slow = slow.next;
        }
        if(slow.next != null) {
            slow.next = slow.next.next;
        }
        return dum.next;
    }
}